Backlighting device for liquid crystal displays

• US 5,739,879 A
• Filed: 11/13/1995
• Issued: 04/14/1998
• Est. Priority Date: 11/13/1995
• Status: Expired due to Term

• Current Assignee: Industrial Technology Research Institute, Taiwan Fluorescent Lamp Co., Ltd.
• Original Assignee: Industrial Technology Research Institute
• Inventors: Tsai, Tzeng-Shii
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): TON, MINH TOAN T
• Application Number:
  US08/555,942
• Time in Patent Office: 883 Days
• Field of Search: 359/49, 359/50, 362/26, 362/31, 349/62, 349/64, 349/71, 349/70, 372/80
• US Class Current: 349/62
• CPC Class Codes: G01D 11/28 Structurally-combined illuminating devices
• CPC Class Codes: G02B 6/0023 provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/133617 Illumination with ultraviolet light; Luminescent elements or materials associated to the cell

Abstract

An improved high energy utilization efficiency backlighting device for liquid crystal displays is disclosed. It comprises: (a) a UV lamp with a UV transmitting quartz envelop for emitting and transmitting UV light; (b) a light guide disposed in front of the UV lamp which allows visible light to travel therethrough, the light guide having a front surface, a rear surface, and a proximal edge surface; (c) a lamp holder with a UV-reflecting interior surface, which, in cooperation with the proximal edge surface of the light guide, encloses the UV lamp; and (d) a fluorescent layer placed between the quartz envelop of the UV lamp and the proximal edge surface of the light guide capable of converting UV light into visible light. In a preferred embodiment, the UV-reflecting interior surface of the lamp holder is formed by coating with a layer of high-purity aluminum. The fluorescent layer is structured such that essentially none of the visible light converted from the UV light will travel therethrough. The fluorescent layer can be disposed on a portion of the exterior surface of the UV transmitting envelop facing the proximal edge surface of the light guide. Or the fluorescent layer can be formed on the proximal edge surface of the light guide. Furthermore, the proximal edge surface can be curved matching the curvature of the quartz envelope to further improve the energy utilization efficiency.

Claims

1. A backlighting device for liquid crystal displays comprising:

(a) a UV lamp for emitting UV light, said UV lamp having a UV transmitting envelop;

(b) a light guide disposed in front of said UV lamp which allows visible light to travel therethrough, said light guide having a front surface, a rear surface, and a proximal edge surface;

(c) a lamp holder with a UV-reflecting interior surface, said UV-reflecting interior surface and said proximal edge surface of said light guide cooperatively enclosing said UV lamp; and

(d) a fluorescent layer placed between an exterior surface of said UV transmitting envelop of said UV lamp and said proximal edge surface of said light guide capable of converting UV light into visible light.

2. A backlighting device for liquid crystal displays according to claim 1 wherein said UV transmitting envelop of said UV lamp is a quartz glass envelop having a transmittance to UV light at 254 nm of at least 90%.

3. A backlighting device for liquid crystal displays according to claim 1 wherein said lamp holder and said fluorescent layer are constructed such that no more than 15% of said visible light converted from said UV light will be intercepted by said fluorescent layer.

4. A backlighting device for liquid crystal displays according to claim 1 wherein said lamp holder and said fluorescent layer are constructed such that essentially none of said visible light converted from said UV light will be intercepted by said fluorescent layer.

5. A backlighting device for liquid crystal displays according to claim 1 wherein said fluorescent layer is disposed on a portion of said exterior surface of said UV transmitting envelop facing said proximal edge surface of said light guide.

6. A backlighting device for liquid crystal displays according to claim 5 wherein said fluorescent layer encompasses an angle of about 60°

to 180°

, measured from a center of said UV-transmitting envelop.

7. A backlighting device for liquid crystal displays according to claim 5 wherein said fluorescent layer encompasses an angle of about 90°

to 120°

, measured from a center of said UV-transmitting envelop.

8. A backlighting device for liquid crystal displays according to claim 1 wherein said fluorescent layer is formed on said proximal edge surface of said light guide.

9. A backlighting device for liquid crystal displays according to claim 1 wherein:

(a) said proximal edge surface has an arcuate shape matching a curvature of said UV-transmitting envelope; and

(b) said fluorescent layer also has a similar arcuate shape so as to allow it to be tightly sandwiched between said UV-transmitting envelop and said proximal edge surface of said light guide.

10. A backlighting device for liquid crystal displays according to claim 1 said UV-reflecting interior surface is formed by coating with a layer of a high-purity aluminum material having reflectivity to UV light at 254 nm of at least 95%.

11. A backlighting device for liquid crystal displays according to claim 1 further comprises a visible light reflector means disposed behind said rear surface of said light guide.

12. A backlighting device for liquid crystal displays according to claim 1 further comprises a diffuser means disposed above said front surface of said light guide.

20. A liquid crystal display according to claim 1 wherein said UV-reflecting interior surface is formed with a layer of a high-purity aluminum material having reflectivity to UV light at 254 nm of at least 95%.

13. A liquid crystal display comprising:

(a) a backlight which comprises;

(i) a UV lamp for emitting UV light, said UV lamp having a UV transmitting envelop;

(ii) a light guide disposed in front of said UV lamp which allows visible light to travel therethrough, said light guide having a front surface, a rear surface, and a proximal edge surface;

(iii) a lamp holder with a UV-reflecting interior surface, said UV-reflecting interior surface and said proximal edge surface of said light guide cooperatively enclosing said UV lamp;

(iv) a fluorescent layer placed between an exterior surface of said UV transmitting envelop of said UV lamp and said proximal edge surface of said light guide capable of converting UV light into visible light; and

(v) a visible light reflector means disposed behind said rear surface of said light guide;

(b) a liquid crystal display panel disposed above said front surface of said light guide; and

(c) a diffuser means disposed between said front surface of said light guide and said liquid crystal display panel.

14. A liquid crystal display according to claim 13 which is a color liquid crystal display.

15. A liquid crystal display according to claim 13 wherein said UV transmitting envelop of said UV lamp is a quartz glass envelop having a transmittance to UV light at 254 nm of at least 90%.

16. A liquid crystal display according to claim 13 wherein said lamp holder and said fluorescent layer are constructed such that less than 15% of said visible light converted from said UV light will be intercepted by said fluorescent layer.

17. A liquid crystal display according to claim 13 wherein said fluorescent layer is disposed on a portion of said exterior surface of said UV transmitting envelop facing said proximal edge surface of said light guide.

18. A liquid crystal display according to claim 13 wherein said fluorescent layer is formed on said proximal edge surface of said light guide.

19. A liquid crystal display according to claim 13 wherein:

(a) said proximal edge surface has an arcuate shape matching a curvature of said UV-transmitting envelope; and

(b) said fluorescent layer also has a similar arcuate shape so as to allow it to be tightly sandwiched between said UV-transmitting envelop and proximal edge surface of said light guide.